1. Technical Field
This invention relates generally to navigation systems and, more particularly, to a mapless GPS based direction pointing navigation system integrated in a vehicle entertainment system such as a car radio and sharing a common display.
2. Discussion
The concepts of intelligent vehicle highway systems (IVHS) are changing the future of ground transportation systems. In particular, navigation systems have been developed and are increasingly becoming available for use in assisting a mobile user. For example, on-board navigation systems are currently provided in some automotive vehicles to assist the driver of the vehicle in navigating the vehicle along a route or roadway system to reach a desired destination.
Early navigation systems generally did not have the availability of advanced positioning systems such as global positioning system (GPS). Instead, a number of early navigation systems often relied exclusively on dead reckoning techniques to account for a moving vehicle's location. Generally speaking, dead reckoning is the determination of position by advancing a known position using measured courses and distances. This generally involved determining a starting location and manually setting the vehicle's position on an electronic map. With the use of a dead reckoning technique, an approximate path of travel of the vehicle could be computed and updated as the vehicle was driven. The travel path determination was often achieved by way of a compass reading and vehicle speed information or was achieved by some other kind of dead reckoning technique. However, many of the dead reckoning based navigation systems often failed to provide accurate and continuous navigation assistance and therefore required repeated corrections to the vehicle's computed position.
The development of the global positioning system (GPS) by the United States Department of Defense has greatly enhanced the ability to navigate. Currently, a constellation of satellites are in place orbiting the earth at high altitudes and transmitting radio waves which contain position information. With the use of GPS receivers, the position information can be received and used to calculate the current latitude and longitude position coordinates at the receiving location. The global positioning system is currently achieving recognition as the superior position locator system for providing accurate worldwide fixes.
With the widespread availability of GPS, more recent navigation systems now rely on GPS to provide position information to compute a vehicle's position. According to one approach, the computed position of the vehicle is contrasted to a digitized map. This technique, also known as map matching, requires a complex digitized map database and normally uses an expensive full function detailed map display to show the digitized map in relation to the vehicle's position. The digitized map database has to consider one-way street information, turn restrictions and other roadway requirements. Often with the use of a complex algorithm, a computer would attempt to compute a best route from the vehicle's current position to a desired destination, considering all available street changes and travel restrictions. This results in turn-by-turn instructions in which a driver is instructed to turn left or right or proceed straight ahead on each approaching street.
The use of map matching navigation and other similar full function navigation systems has generally provided a user with the ability to follow calculated turn-by-turn instructions as computed by the navigation system. However, map matching techniques generally do not take into consideration changes in travel routes and roadway restrictions. That is, changes in a transportation system which often occur, especially on roads subjected to road construction, remain unaccounted for. Also, some drivers may feel that the expensive full function displays may tend to cause the drivers to rely too heavily on the map display for driving instructions rather than for mere assistance. They therefore may feel that such displays are too distractive. Furthermore, most full function navigation systems are commercially available at a very high cost which often makes the systems unaffordable to a vast majority of consumers.
Additionally, the commercially available full function navigation systems require a separate active matrix with an expensive mappable graphics display such as a liquid crystal display (LCD). Detailed mappable displays such as the LCD tend to be rather bulky and difficult to mount in a vehicle for easy viewing. In addition, the on-board computer and associated electronics in several conventional full function navigation systems are separately packaged and difficult to accomodate in a vehicle.
It is therefore desirable to provide a low cost and easy-to-use navigation system which offers navigational assistance to a mobile user for traveling to desired destinations.
More particularly, it is desirable to provide a mapless navigation system that employs global positioning system signals and destination database and provides destination direction pointing assistance in a manner which is affordable to many users.
It is further desirable to provide a mapless navigation system which may easily be integrated into an audio entertainment system and installed in an automotive vehicle for use in assisting the driver of the vehicle to reach a desired destination.
Yet, it is also desirable to provide such a navigation system which shares a common display with an audio entertainment system to display navigational information.